<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <div id="app">
        <h1>{{msg}}</h1>
        <button @click="change">逆转世界</button>
    </div>
    <script src="./vue.js"></script>
    <script>
        const app = new Vue({
            el: '#app',
            data: {
                msg: 'Hello, World',
                msg1: 'dlroW ,olleH',
                msg2: 'Hello, World'
            },
            methods: {
                change() {
                    if (this.msg === this.msg1) {
                        this.msg = this.msg2
                    } else {
                        this.msg = this.msg1
                    }
                }
            }
        })
    </script>
</body>

</html>